A few of you may remember the block-pushing Flash puzzle game Psychopath. One of its players made (with permission) a similar game for Android called Mental Block, which you can see here. It's free with no ads. I thought it might appeal to the XKCD demographic.

So, how far can you get? There are 5 worlds with 10 levels each; I think the level selection is quite good (and not just because some of my levels are in there, haha).

If this isn't appropriate here (is it okay to plug a game I helped make levels for?), let me know and I'll remove it.